In micro-processing for manufacturing a semiconductor device or a FPD (Flat Panel Display) using plasma, it is very important to control a temperature or a temperature distribution of a processing target substrate (a semiconductor wafer, a glass substrate, etc.) as well as to control a plasma density distribution on the processing target substrate. If the temperature control of the substrate is not properly performed, not only the uniformity of a surface reaction of the substrate but also the uniformity of process characteristics may not be achieved, so that a production yield of semiconductor devices or display devices is decreased.
In general, a mounting table or susceptor, which mounts thereon a processing target substrate within a chamber of a plasma processing apparatus (particularly, a capacitively coupled plasma processing apparatus), has a function as a high frequency electrode that applies a high frequency power into a plasma space, a function as a holder that holds thereon the substrate by electrostatic attraction or the like, and a function as a temperature controller that controls the temperature of the substrate to a preset temperature through heat transfer. As for the temperature control function, it is required to appropriately correct a heat input characteristic distribution of the substrate affected by non-uniform radiant heat from plasma or a wall of the chamber, or a heat distribution affected by a substrate supporting structure.
Conventionally, in order to control the temperature of the susceptor and, further, the temperature of the substrate, a heater structure is widely employed. In this heater structure, a heating element that generates heat by an electric current applied thereto is provided in the susceptor, and Joule heat generated by the heating element is controlled. When using this heater structure, however, a part of a high frequency power applied to the susceptor from a high frequency power supply may be easily introduced into a heater power feed line through the heating element as a noise. If this high frequency noise reaches a heater power supply through the heater power feed line, operation and performance of the heater power supply is degraded. Furthermore, if a high frequency current flows in the heater power feed line, the high frequency power may be wasted. Typically, to solve these problems, a filter that reduces or blocks the high frequency noise flowing from the heating element embedded in the susceptor is provided on the heater power feed line.
The present applicant describes, in Patent Document 1, a filter technique that provides improved stability and reproducibility of filter performance for blocking a high frequency noise introduced to a line such as a power feed line or a signal line from an electrical member other than a high frequency electrode within a processing vessel of a plasma processing apparatus. This filter technique employs a regular multiple parallel resonance characteristic of a distributed constant line. Accordingly, only one coil is provided within the filter, and, also, stable noise blocking characteristic less affected by the apparatus difference can be obtained.
Further, the present applicant also describes, in Patent Document 1, a technique of a parallel resonance frequency adjuster capable of controlling at least one of multiple parallel resonance frequencies by locally changing characteristic impedance of the distributed constant line by way of, for example, coaxially providing a conductive ring member between the coil and an outer conductor. Since at least one of the multiple parallel resonance frequencies can be set to be equal to or approximate to a frequency of a high frequency noise to be blocked, sufficiently high impedance as required can be applied to the frequency of this high frequency noise by the parallel resonance frequency adjuster. Thus, the heater power supply can be protected securely, and reproducibility and reliability of the plasma process can be improved.
Patent Document 1: Japanese Patent Laid-open Publication No. 2011-135052